They've got two pilots onboard and notice how the nose is up with CG a bit aft. It probably won't fly single pilot within CG limits without a ballast.

Hi Soave_Pilot,

seems like you missed one or two hours in ground school....
Main gear boxes and therefore main rotors are normally rigged with an angle toward the front of the helicopter - which allows more or less level seating while at cruising speed (fuselage level, rotor tilted forward for speed).
The little drawback is, that you hover tail low (rotor level, fuselage tilted backwards)
http://www.helionline.net/picture/41196/big.jpg
and I remember my Bell 206 times, with some very interesting high nose up attitudes, cause my weight was just above the weight, where you required an extra weight in front.
Slightly lighter pilots had to carry them...

additional, with a test flight, you can be quite sure, that the EC120 was filled with additional electronics, to record every possible movement, vibration, temperature and so on - which you can see in the clip, is also in the back of the helicopter.
Watched the clip and saw nothin unusual about the attitude of the helicopter.
http://www.helionline.net/photogalle...//4/EC120.html

One hopes that the Fuel Control unit is not designed by Volkswagen Audi :O

I don't know.... it would give lower emissions, on paper at least :) (Just don't use the official consumption figures for any flight planning, if you want to avoid unpleasant surprises :eek:)

Thanks for the review mate. I think I can go solo now :ok:


I was talking about the CG of that aircraft. Here below you have a EC120 with 2 pilots onboard, notice how the tail is not as low as the EC120 with diesel engine. And like you said, they had more electronics in the back, take those out and you would have an even higher nose.

Happy flying


http://avia-dejavu.net/OO-EYP1.jpg

http://avia-dejavu.net/OO-EYP1.jpg

Hi Soave_Pilot,

in the physics of my world - if you remouve weight from behind the rotor - the nose starts to drop.......

∧-------∆--------∨

:E

You are correct. But I meant back seat inside the helicopter as I thought it was referred.

SP

I only have around 650 hours on an EC120 so not that many, but I've found they always run out of FWD CG. Personally I think if they did adopt a more rear heavy configuration then it may solve a few problems with CG issues.

For those solo flights just carry some ballast.

On my machine (floated, with my avionic fit, 1148kg empty), with just a pilot, then provided the pilot weighs more than 20kg you will be inside the rear CoG limit.


As Heli190 says, it is very easy to run out of fwd CoG on the 120 if you want to lift 5 guys. Say 4x90kg guys (Pilot and 3 pax) then I have just 60kg left in the final rear seat and then out of fwd CoG.


So weight reduction behind the mast will begin by improving both total payload and flexibility for GoG.

I'm guessing the fuel tank can be designed smaller too as diesel fuel burn should be a lot less than a turbine.

120 has 2x fuel tanks, one under the baggage compartment floor and the other higher. Smaller fuel load will help total weight but with the current tank locations very little impact on CoG; there is some small shift FORWARD as fuel reduces but it is minimal. If the redesign removed the front of the current tank you might reach neutral CoG from ramp-to-zero fuel.

This recip diesel engine retrofit is not fully optimized in terms of weight. In order to make use of the 120's MGB there is actually a speed increasing gearbox installed between the diesel engine and existing MGB input. The diesel engine output speed is increased and then decreased.

Here is a fairly recent presentation from Airbus Helo on the HCE demonstrator program: http://www.aerodays2015.com/wp-conte...ierczynski.pdf Interesting technical data on fuel consumption, emissions, and drivetrain dynamics. Also note the relative size of the heat exchanger module on slide 5. Overall a pretty nice job of packaging.

nice piece of information, indeed nice packaging, fully machined body, wow!, $$$.


I almost like the idea of it now. reliability question is still something that would deserve more information experience.


and then that sexy turbine spin up noise will be gone :(

What sort of SHP is needed to be had for running the EC120, and what sort of Diesel Engine would be fitted, would it be a big six, or V6 upright or inverted, or the same with a V8 or V10, V12, the twin turbo V6 in my Jaguar develops 295 HP in normal guise but will push out near 350 if chipped and is still only weighing about 280 Lbs the torque is huge all the way through the acceleration range due to Turbo's overlapping each other,

If kept at 80 mph or below,this engine return's 38/40 mpg whilst only running at 1850 rpm it is turbine smooth, al-told this is one of the best Diesel engine's I have come across.. or are we thinking of a true Turbine burning true Diesel..?

The EC120 turbine puts out 504hp and it's not enough.So, 550 to 600 would be good.

Peter-RB, the presentation above answers your questions quite well.

I think the 120 "not enough power" issue relates more to the gearbox limitations that the engine. Hence I can't see value in producing (say) 800 SHP from the test motor and simply trashing the gearbox.


Whilst the current approach is great for testing the motor, surely a production aircraft would have a new gearbox, doing away with the idea of a multiplier box. In that case it is a perfect time to increase the blade area and uprate overall power.


Not for "cheap retrofit" (obviously) but a very sensible solution and still minimising the additional certification / testing.

120 has plenty enough power!

Any more and it will eat into 350B2 territory and price itself out of the market.

Funny that no one ever complains about the Bell 206 not having enough power.

Keep the ec120 inside published limits and it has plenty of power - just MANAGE the weight!

You would NEVER think about using the 96 (or was it 98??) gallons on the range-extender on a 206 and put 3 pax in there!! (it would never take off!)

But for some reason everybody thinks you should be able to fill a 120 to 110 gallons and put 4 pax in there and probably fill the trunk too AND fly off with this!!

....as long as you stay within the weight limits you fly circles around a 206, just fine - thank you!


3top :cool:

GoodGrief- The Arrius 2F turboshaft engine used on the H120 is rated 432shp for TO and 432shp for MCP. The HIPE AE 440 V8 diesel has a similar rating. As John R81 noted the shp rating is based on the MGB capabilities. This is illustrated by the vertical line shown in the center of the graph on slide 4 of the presentation I linked above.

John R81- Your point about the H120's existing MGB capability is excellent. One serious concern when retrofitting this recip diesel engine with very high firing pressure is the instantaneous torque profile at the crankshaft. If you look at the graph on slide 9 of the presentation I linked above, it shows a crank torque oscillation of +/-100% at 4X/rev. Turboshaft engines don't produce these extreme peak-to-mean torque oscillations, and a turboshaft engine MGB is not designed to accommodate them. To address this problem, a tuned torsion shaft was installed between the engine and gearbox.

That presentation had some great technical information. I think any publicly funded research project that does not involve some national security related subject matter should be made freely accessible to the public on a timely basis. I congratulate the EC and its industry partners on this program for doing a good job in this regard.

The point of the motor torque spikes compared to turbine is well taken, the magic of helicopters is that they operate a one unique RPM setting (various torque settings). as the result a tuned damper shaft is bound to give good result in a small volume. This is in opposition to the automobile where the combustion engine vibration have to be absorbed across a wide range of operating points.


The engine is 100Kg heavier, the fuel is 100Kg lighter, this could work.


I do come back to the idea, what will be the reliability and maintainability of that engine compare to a turbine?. It will take a full package of benefit to convince operator and private owners. the EC120 is a great aircraft, but it is not selling so much out of the factory anymore if I am not mistaking.


Commercially, should airbus helicopter focus on it, or make more high priced EC135/EC145.... with the growth from Eurocopter to airbus helicopter, they got bigger, they therefore have to think bigger (similar to Sikorsky/Lockeed dumping the 300).